In a straddle-type vehicle, there is a known technique in which if the vehicle is driven such that a rotating speed of an engine or a vehicle speed reaches a prescribed value, the engine rotating speed or the vehicle speed does not exceed the prescribed value. Such a known technique is described, for example, in Japanese Laid-open Patent Application Publication No. 2006-104953.
According to the technique described in Japanese Laid-open Patent Application Publication No. 2006-104953, in a motorcycle having an electronically controlled throttle among the straddle-type vehicles, if an engine rotating speed or a vehicle speed reaches a prescribed value, an opening degree of a throttle valve is reduced lower than a standard opening degree of the throttle valve in accordance with an accelerator operation amount. As a result, an air intake amount is reduced and the engine output is limited. With this, the engine rotating speed or the vehicle speed is limited such that the speed does not exceed the prescribed value. The technique described in the Japanese Laid-open Patent Application Publication No. 2006-104953 is characterized in that the combustion stability of the engine can be enhanced when the output is limited as compared with a conventional technique in which the engine output is limited due to cutting or reducing the engine ignition or due to stopping of the fuel supply. Therefore, it is possible to prevent the driver ride comfort and exhaust performance from deteriorating.
However, in the straddle-type vehicle described in the Japanese Laid-open Patent Application Publication No. 2006-104953, a control for decreasing the opening degree of the throttle valve is started when the speed reaches the prescribed value. Therefore, if the control is performed such that the speed does not exceed the prescribed value, the ride comfort (decelerating feeling is generated) deteriorates, and there is a fear that the speed exceeds the prescribed value in some cases.